[Info-vax] RSTS/E and VMS connection

[Johnny Billquist]

On 2023-04-07 01:02, bill wrote:
> 
> WE have often heard that VMS on the VAX was the logical procession
> from RS11 on the PDP.  I was looking around at my bookshelf and saw
> my 1983-84 RSTS/E PDP-11 Operating System book and it kinda piqued
> my interest so I picked it up and did a  little lite reading.

Well. Internally, VMS is like a scaled up RSX in many (most?) corners. 
Most data structures and designs were (are) more or less the same as in 
RSX, but scaled up for 32-bits and whatever logically came out from 
there. A lot of system calls is the same story. And initial release of 
VMS mostly used all RSX cusps, running in compatibility mode, and slowly 
getting replaced with native things. Early versions of VMS I seem to 
remember even might still have used ODS-1, or some hybrid between ODS-1 
and -2. I clearly remember the 9+3 character filename limitation in my 
earliest memories of VMS.

However, at the user interface level, VMS was clearly taking it's queues 
from RSTS/E. Including having the BASIC+ SYS() calls compatibly working 
in VMS. And things like ^C actually stopping the program, unlike under 
RSX, where it just gives you the CLI prompt.

> And there is another note about "The RSTS/E and VAX/VMS Compatbility
> Manual".  I would love to see a copy of that.

There was also a manual/book about moving from RSX to VMS published. I 
think DEC tried to address both crowds, and convince them both to 
migrate to VMS. However, I think they were much more successful in 
convincing the RSTS/E guys.

   Johnny